With the change of the time and the audience classes, music works have been changing from well-organized and rigorous symmetrical in the 18th century to romantic freedom and expressing strong self-consciousness in the 19th century. In the 19th century, both the performer to the composer promoted the new artistic ideals, incorporating legendary, fantasy and unreal, these elements called "romantic" into music works. In this thesis, the author will discuss the "ambiguous" compositional technique which is the most important element of the romantic music works.

This thesis includes five chapters. In the first chapter, "An Outline of Brahms’ Life and Compositional Periods", which explore that Brahms’ important turning points in his life and his compositional style in different periods of his life. Moreover, the author will discuss what’s the reasons for his change. "The Compositional Feature of Brahms sonata for piano and violin No. 1 in G major, op. 78" is the second chapter. The author will analyze the main motivation and the theme of this work, and then discuss more detailly of the style and sound effects created in all three movements. Finally, the author will illustrate the special rhythm and unique compositional technique. Thirdly, " The Background and Structure ", the author will focus on the characteristics of Brahms' chamber music works and explore the background of his works at first. In addition, the author will explore the use of motivation and the change of rhythms. Fourthly, "The Polyrhythmic Period", the author will divide the sections of composition into Hemiola and triplets over duplets methods, and further classify them according to their types. Finally, "Conclusion", this chapter is a summary of this thesis, and contains the what the author learn within the process of writing this thesis.